The most common signs of heart disease are angina (chest pain), heart palpitations, and breathlessness. Often if it is believed a patient may be experiencing heart disease, his or her doctor will take a comprehensive approach, using multiple tests, patient history, and a physical exam. The first step is often to look into the patient’s family history, look for high blood pressure, and take bloodwork to determine if the patient’s cholesterol level is dangerously high. If some of the typical signs and symptoms of CHD are seen, the doctor will go on to perform some tests.
One of the first tests used is often an electrocardiogram (EKG), which records the electrical activity of the heart. Each wave on the EKG represents a step in the heart beat process: the P wave represents atrial contraction (depolarization), the QRS complex represents ventricular contraction (depolarization), and the T wave
represents the heart returning to its resting state (repolarization). The most important trends medical professionals look for on an EKG report in a patient who potentially has heart disease are ST elevations and Q waves. ST elevations are a visible, heightened section between where the S and T waves normally occur. These may suggest a coronary artery is blocked and the full thickness of the heart muscle is damaged. This alone is not sufficient for a proper diagnosis, however.
Another test that may be performed is an exercise stress test. This requires a patient to exercise by riding a stationary bike or walking on a treadmill while having his or her heart rhythms and blood pressure monitored. The exercise continues until: (1) his or her heart rate is at least 85% of its maximum rate, (2) the patient explicitly expresses he or she can no longer exercise and wants to stop, or (3) signs of heart trouble arise, such as changes in blood pressure or arrhythmia.
The “basic” form of the exercise stress test uses only an EKG, but other variations exist. For example, an echocardiogram can be used to actually visualize heart action and blood flow with ultrasound images. For patients that are physically unable to exercise, drugs can be administered that mock the stress exercise puts on the heart. In this situation, the same monitoring would take place, simply after the drug is taken as opposed to while exercise takes place. Following these measurements, interpretation of the results will take place. There are several factors that are often looked at, including the capacity of the patient to exercise and reach the goal metabolic rate, heart rate increase, how easily the heart rate returns to normal after exercise has ceased, oxygen levels, changes in blood pressure, and the trends of the ST waves of the EKG. All of these factors, when used in combination, often create a reliable and accurate picture for the doctor of the patient’s risk for or presence of heart disease. An echocardiogram alone can also give insight into the condition of the heart, as the ultrasound images allow the doctor to see if there is damage to the heart muscle and, if so, the extent of this damage.
Once diagnosed with CHD, the severity of the disease can be discovered using radionuclide imaging. Radioactive tracing elements are inserted intravenously into the affected patient. These elements can be detected as they pass through regions of interest in the heart, and imaging techniques and computer analysis is used to plot the flow and movement of the tracers-- and thus the blood as well. It is common that this technique is used in conjunction with an exercise stress test to either determine the severity of heart disease, the success of a previously implemented treatment plan for heart disease, or if a heart attack has occurred. When the two techniques are used together, the procedure is known as the Myocardial Perfusion Imaging Test, also known as the Thallium Stress Test. An MRA or CT scan may also be used to evaluate the severity of heart disease in a patient who has already been diagnosed [6].
